Alcohol use within the college student population is both widespread and problematic1,2,3. There are many negative consequences associated with frequent alcohol use, ranging from mild (e.g., hangovers, missed classes) to severe (e.g., DUIs, assault, death)4,5. Popular online interventions targeting alcohol use among college students reduce alcohol consumption and associated problems6,7. However, online interventions are not as efficacious as face-to-face interventions8. The proposed project will employ emailed boosters in a randomized, controlled trial in an effort to improve the efficacy an existing, popular, free online intervention, Alcohol 101 PlusTM9, while at the same time maintaining low cost and easy dissemination. Boosters have been used successfully for alcohol use interventions among those seeking injury treatment in emergency medical settings10,11,12. Despite these successes, prior research has not supported booster efficacy for college student alcohol interventions6,13. The proposed project seeks to develop and evaluate the effectiveness of boosters for a widely-used college student alcohol intervention by improving on the design of boosters. Specifically, the present project will improve boosters by providing easy access via email to minimize burden; providing succinct, personalized feedback; and providing reminders of protective behavioral strategies (PBS). PBS have consistently predicted reductions in alcohol-related problems1,14,15,16. The proposed study will critically examine the issue, including the manipulability of PBS use. The online intervention includes PBS as one component of education, and proposed boosters target these behaviors specifically. The proposed research will address the following specific aims: Aim 1: Improve the efficacy of an easily-disseminated computerized intervention by adding personalized follow-up boosters, where efficacy is evidenced by reduced drinking and related problems. Aim 2: Extend the duration of the reduction in drinking and associated problems through the use of these personalized follow-up boosters. Aim 3: Examine protective behavioral strategies highlighted by the intervention as mediating behavioral mechanisms of change. Experimental Protocols: Participants will be assessed on key constructs, then will be randomized to receive the intervention or not. To test the effectiveness of adding boosters, participants randomized to alcohol intervention boosters will receive emails 4 weeks after the intervention with tailored feedback based upon their reported alcohol consumption after the intervention. Participants will initially be assessed biweekly, then every three months up to nine months. Significance: The proposed study will be a critical first step in launching a programmatic line of research to adapt existing online interventions and develop future interventions that include PBS as a major program component. The findings from this study will be used to identify implications for modifying the protocol or booster. These will drive the hypotheses for subsequent studies in this program of research.